Improved biomechanical performance leads to better vessel management and reduction in chronic vascular injury
It is the performance of the entire femoropopliteal segment that is important in determining the durability of femoropopliteal stenting, not just the stent placed in one part of it. Important limitations inherent in straight laser-cut Nitinol stents include a tendency to straighten natural vascular curvature, causing suboptimal flow conditions and interference with femoropopliteal vessel shortening during knee flexion/extension, which increases the risk of kinking within the stented and unstented vessel segments. The consequence is not just an increased risk of stent fracture but also of chronic vessel injury of the unstented segment, leading to sub-optimal clinical performance. Femoropopliteal artery shortening in a normal vessel (see A below) may reach as much as 23% when the knee bends to 90°, whereas restricted shortening is evident when a straight stent is present in the vessel, as this type of stent has limited capacity to shorten. The problem is further complicated by the tendency of the straight stented vessel to kink and/or buckle as the compressive stress becomes localised (see B below), risking stent fracture and chronic vascular damage. Veryan’s BioMimics 3D stent innovation enables the stented femoropopliteal vessel to shorten more naturally under the compressive load applied during knee bending (see C below), reducing stent fracture risk and vessel damage both within the stented segment and distal to it.
As the knee flexes toward 90⁰, axial compression in normal femoropopliteal artery is taken up by elastic shortening
Straight stent resists compression, strain becomes localised in stent, risking kinking, fracture and vessel damage
Biomimetic stent distributes strain over the whole stent, reducing risk of kinking and fracture. Vessel shortening is accommodated, helping to mitigate the risk of vessel injury at stent ends
Example of Veryan’s 3D stent in axial compression with knee bent at 90⁰ (MIMICS Study subject)
In summary, the development of Veryan’s 3D Nitinol, self-expanding stent technology was directed not only to harness flow-mediated benefits through its biomimicry of arterial three dimensional geometry, but also to provide superior biomechanical performance compared to straight Nitinol stents. Results from preclinical animal and human cadaver studies, together with data from a randomised controlled trial, Mimics study, provide confirmation that the BioMimics 3D stent can be delivered safely, accurately and with an excellent level of procedural success using a simple pin & pull delivery system and standard stenting technique.